Update dependency prettier to ^2.7.1

Author: renovate[bot]

package-lock.json

@@ -51,7 +51,7 @@
     "firebase-functions-test": "^0.2.3",
     "jasmine-core": "^3.6.0",
     "lib-tools": "^2.0.4",
-    "prettier": "^2.2.1",
+    "prettier": "^2.7.1",
     "protractor": "~7.0.0",
     "ts-node": "^9.1.1",
     "tsickle": "^0.39.1",